perf hists browser: Indicate which callchain entries are annotated

Now that we can annotate entries in a callchain, show which ones have an
associated symbol and samples, by adding a right arrow just before the
symbol name when in verbose mode.

To toggle verbose mode press 'V'.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: David Ahern <dsahern@gmail.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-d2rf1p3h5gdp7hdl2gf2bozl@git.kernel.org


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>